A tissue usually contains cells inside a biological matrix, which provides mechanical strength to the tissue. The tissue disruption and cell lysis steps are required for isolating cells, nucleic acids or proteins from the tissue.
Conventional tissue disruption and cell lysis processes are time-consuming and labour-intensive. They employ motorised mechanical homogenisers that have a blender-like component to generate shear force, which physically breaks up the solid tissues and release the cells within. Following this, the cells are subjected to chemical, mechanical or thermal treatment to lyse the cells in order to extract the intercellular and/or intracellular components.
Other ways of tissue disruption adaptable for use with micromechanical and/or automated processes are available which employ enzymolytic tissue disruption methods (WO 2004/046305 incorporated by reference herein).
Disruption of spores and cells by sonification has also been reported [P. Belgrader et. al., Anal. Chem., 1999, 71:4232-4236; Belgrader et. al., Biosensors and Bioelectronics, 2000, 14:849-852; Taylor et. al., Anal. Chem., 2001, 73:492-496]. However, these are applicable for cell lysis and are not feasible for disrupting tissue. Further, the sonicating devices are external devices and are not integrated in an automated system such as μ-TAS or MEMS.
Piezoelectric material has been used as an external means for actuation to bring about cell lysis [P. Belgrader et. al., Anal. Chem., 1999, 71:4232-4236]. However, a high voltage is usually required to actuate the piezoelectric material and further, due to the material's heat conduction, an insulant is required to prevent an increase in temperature from degrading the cells. This makes it difficult to incorporate the piezoelectric material in a micro device.
A fully-integrated biochip for the detection of pathogenic bacteria has also been reported [R Liu et. al., Anal. Chem., 2004, 76(7):1824-1831]. The piezoelectric disc in the biochip only serves to increase the mixing efficiency of fluids within the biochip. It also comprises electrical connections and a printed circuit board within the chip. The presence of electrochemical pumps, and electrical connections integrated within the biochip make the biochip too expensive for mono-use (disposable) applications.
There is therefore a need in this field for inexpensive disposable devices useful for the treatment of biological sample, in particular biological tissues.